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Question 18M.2.hl.TZ1.3c.i

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Date May 2018 Marks available [Maximum mark: 2] Reference code 18M.2.hl.TZ1.3c.i
Level hl Paper 2 Time zone TZ1
Command term Determine Question number c.i Adapted from N/A
c.i.
[Maximum mark: 2]
18M.2.hl.TZ1.3c.i

This question is about ethene, C2H4, and ethyne, C2H2.

(c.i)

Under certain conditions, ethyne can be converted to benzene.

Determine the standard enthalpy change, ΔHΘ, for the reaction stated, using section 11 of the data booklet.

3C2H2(g) → C6H6(g)

[2]

Markscheme

ΔHΘ = bonds broken – bonds formed

«ΔHΘ = 3(C≡C) – 6(CC)benzene / 3 ×  839 – 6 ×  507 / 2517 – 3042 =» –525 «kJ»

 

Award [2] for correct final answer.

Award [1 max] for “+525 «kJ»”.

Award [1 max] for:

«ΔHΘ = 3(C≡C) – 3(C–C) – 3(C=C) / 3 ×  839 – 3 ×  346 – 3 ×  614 / 2517 – 2880 =» –363 «kJ».

[2 marks]

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